1. OBJECTIVES: a. Overall Objectives: Our long-term objective is to delineate the immunological parameters associated with infertility either uninduced or invoked. Sera and semen from patients with unexplained infertility, and sera from vasectomized males, will be analyzed for circulating immune complexes, various antibodies and levels of immunoglobulin and complement components. These studies will enable us to evaluate the safety, from an immunological standpoint, of vasectomy, correlate changes in various immunological parameters, and define the means by which perturbations of the immune system affect fertility. Furthermore, the identification of characteristics unique to these men whose response to vasectomy includes potentially harmful immunological changes could lead to means for screening of candidates prior to this procedure. b. Goals for the Current Year: 1) The ongoing prospective study of the immunological consequences of vasectomy will be paralleled by an analysis of sera from men vasectomized five years previously. In this way, short-term and long-term immunological consequences of vasectomy can be compared. In addition, the analysis of larger numbers of men in our prospective vasectomy study will enable us to more clearly discem correlations between alterations in various immunological parameters. The specificity of the antibody reactive with peripheral T lymphocytes will be defined in order to better assess the neans of its formation and most probable consequences. Similarly, the identity of the circulating sperm antigen(s) in these patients will be determined. 2) The properties of circulating immune complexes in the sera of vasectomized men will be determined and assays will be developed to characterize their antigen, antibody and complement components. With this information we can begin to classify the types of immune complexes formed after vasectomy. 3) We have obtained data indicating that seminal fluid from an infertile man contained an tisperm secretory IgA. We will now screen semen, prostatic fluid and sera from additional patients to assess the frequency of this occurrence and its relationship to infertility. Furthermore, the presence of IgA-containing CICs in seminal plasma will be evaluated.